1. Field of the Invention
The present invention relates to an object, a method, or a manufacturing method. In addition, the present invention relates to a process, a machine, manufacture, or a composition of matter. In particular, one embodiment of the present invention relates to a semiconductor device, a display device, a light-emitting device, a power storage device, a storage device, a driving method thereof, or a manufacturing method thereof.
In this specification and the like, a semiconductor device generally means a device that can function by utilizing semiconductor characteristics. A transistor and a semiconductor circuit are embodiments of semiconductor devices. An arithmetic device, a memory device, an imaging device, an electro-optical device, a power generation device (e.g., a thin film solar cell and an organic thin film solar cell), and an electronic device each may include a semiconductor device.
2. Description of the Related Art
Interesting properties of oxide containing indium and zinc have been widely researched (Non-Patent Document 1 and Non-Patent Document 2). Non-Patent Document 1 discloses that a homologous series represented by In1−xGa1+xO3(ZnO)m (−1≤x≤1, and m is a natural number) exists. Furthermore, Non-Patent Document 1 discloses a solid solution range of a homologous series. For example, in the case where powders of In2O3, Ga2O3, and ZnO are mixed and sintered at 1350° C., in a solid solution range of a homologous series when m is 1, x is within a range from −0.33 to 0.08, and in a solid solution range of a homologous series when m is 2, x is within a range from −0.68 to 0.32.
A compound represented by AB2O4 (A and B are metal) is known as a compound having a spinel crystal structure. In addition, Non-Patent Document 1 discloses an example of InxZnyGazOw, and when x, y, and z are set so that a composition in the neighborhood of ZnGa2O4 is obtained, i.e., x, y, and z are close to 0, 1, and 2, respectively, a spinel crystal structure is formed or is likely to be mixed.
A technique in which a transistor is formed using a semiconductor material has attracted attention. The transistor is applied to a wide range of electronic devices such as an integrated circuit (IC) or an image display device (also simply referred to as a display device). As semiconductor materials applicable to the transistor, silicon-based semiconductor materials have been widely used, but oxide semiconductors have attracted attention as alternative materials.
For example, a technique for formation of a transistor using zinc oxide or an In—Ga—Zn-based oxide semiconductor as an oxide semiconductor is disclosed (see Patent Documents 1 and 2).
In recent years, demand for integrated circuits in which semiconductor elements such as miniaturized transistors are integrated with a high density has risen with increased performance and reductions in the size and weight of electronic devices.